// Copyright (c) Microsoft Corporation
// All rights reserved.
//
// MIT License
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
// documentation files (the "Software"), to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and
// to permit persons to whom the Software is furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED *AS IS*, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
// BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

export default class Pagination {
  /**
   * @param {number} itemsPerPage
   * @param {number} pageIndex
   */
  constructor(itemsPerPage = 20, pageIndex = 0) {
    this.itemsPerPage = itemsPerPage;
    this.pageIndex = pageIndex;
  }

  /**
   * @param {any[]} items
   * @returns {any[]}
   */
  apply(items) {
    const { itemsPerPage, pageIndex } = this;
    const start = itemsPerPage * pageIndex;
    const end = itemsPerPage * (pageIndex + 1);
    return items.slice(start, end).map(item => {
      item.key = item.username;
      return item;
    });
  }
}
